Fresenius Medical Care multiFiltrate, Instructions For Use Manual

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Chapter 7: Functional description
7-6 Fresenius Medical Care multiFiltrate IFU-EN-UK 15A-2015
CVVHD With CVVHD, the blood is purified mainly through dialysis. In addition to
solute transport through diffusion, which is the main process for
removing toxins in this case, a certain amount of convection also takes
place within the filter and by volume removal. Under typical CRRT
conditions, where the blood flow is considerably higher than the
dialysate flow, an almost complete saturation of the dialysate with toxins
of a low molecular weight, such as urea and creatinine, can normally be
expected. The efficacy of a CVVHD procedure is therefore comparable
with that of a Post CVVH procedure. As the speed of diffusion is relative
to the molecular weight, the full saturation of the dialysate with larger,
middle-molecular weight solutes may not be achieved, depending on
the blood and dialysate flow rates set. The clearance rate achieved for
these substances is thus lower than with Post CVVH (if the same
dialysate and substituate quantities are used). This disadvantage of
CVVHD can be compensated at least partially through the use of filters
with a large active surface and high-flux membranes. The advantage of
CVVHD lies in the possibility of setting a lower blood flow than in
Pre CVVH and Post CVVH.
Treatment parameters
CVVHD (adults) Min. Max. Resolution Unit
Blood flow 10 500 10 ml/min
Ultrafiltration Off / 10 1800 10 ml/h
UF goal Off / 50 10,000 50 ml
Cont. heparin adm. Off / 0.1 25 0.1 ml/h
Dialysate 600 4800 50 ml/h
Temperature Off / 35 39 0.5 °C